In recent years, in the field of paints, conversion from organic solvent-based paints to water-based paints has been attempted from the viewpoints of environmental protection and health and safety. However, water-based paints are insufficient in coating performance of weather resistance, water resistance, and stain-resistance in comparison with organic solvent-based paints. Therefore, the development of water-based paints has been conducted for solving these problems.
For instance, Patent Literature 1 discloses a low stain aqueous coating material including an acrylic resin emulsion and colloidal silica, where the acrylic resin emulsion has a minimum film-forming temperature of 15° C. or more.
Patent Literature 2 discloses an aqueous coating material containing an aqueous emulsion and colloidal silica, where the aqueous emulsion is obtained by polymerizing hydrolyzable silyl group-containing monomers with a nonionic surfactant in an aqueous emulsion of acrylic resin having a cross-linking structure.
Patent Literature 3 discloses an aqueous coating material containing an acrylic polymer, colloidal silica, and a nonionic surfactant, where the acrylic polymer is obtained by copolymerization of monomers having two radically polymerizable groups.